Evaluation of Surface Roughness and Subsurface Damage of 4H-SiC Processed by Different Finishing Techniques

2012 ◽  
Vol 523-524 ◽  
pp. 19-23 ◽  
Author(s):  
Hui Deng ◽  
Kazuya Yamamura
Keyword(s):  
Surface Roughness ◽  
High Hardness ◽  
Cross Sectional ◽  
Damage Layer ◽  
Transmission Electron ◽  
Chemical Inertness ◽  
Single Crystal Sic ◽  
Device Applications ◽  
Atomically Flat ◽  
Machining Characteristics

Single crystal SiC is one of the most attractive semiconductor materials for next generation power device applications. However, it is very difficult to be precisely machined due to its high hardness and chemical inertness. We evaluated the machining characteristics of 4H-SiC using different processes including diamond abrasives lapping, chemical mechanical polishing (CMP) and plasma assisted polishing (PAP). Scratches were introduced through diamond abrasives lapping due to the high hardness of diamond, which resulted in the worsening of surface roughness. A damage layer was observed in the cross-sectional transmission electron microscopy (XTEM) images. A scratch-free surface was obtained through CMP, but it’s not atomically flat since step/terrace structure couldn’t be clearly observed. PAP was newly proposed for the finishing of difficult to machine materials. In PAP, water vapor plasma oxidation and soft abrasive polishing were repeatedly conducted. Ceria which is much softer than SiC was used as the abrasive material. PAP was proved very effective to achieve surfaces out of scratches. Also, due to the low hardness of ceria, no damage layers were introduced. The roughness of PAP processed surface was decreased to about 0.1 nm rms. The surface was also observed by XTEM, which proved an atomically flat surface without crystallographical damage was obtained.

scholarly journals Surface improvement of organic photoresists using a near-field-dependent etching method

2017 ◽  
Vol 8 ◽  
pp. 784-788 ◽  
Author(s):  
Felix J Brandenburg ◽  
Tomohiro Okamoto ◽  
Hiroshi Saito ◽  
Benjamin Leuschel ◽  
Olivier Soppera ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Absorption Edge ◽  
Near Field ◽  
Light Sources ◽  
Etching Technique ◽  
Cross Sectional ◽  
Surface Flattening ◽  
Carrier Scattering ◽  
Atomically Flat ◽  
Scattering Losses

Surface flattening techniques are extremely important for the development of future electrical and/or optical devices because carrier-scattering losses due to surface roughness severely limit the performance of nanoscale devices. To address the problem, we have developed a near-field etching technique that provides selective etching of surface protrusions, resulting in an atomically flat surface. To achieve finer control, we examine the importance of the wavelength of the near-field etching laser. Using light sources at wavelengths of 325 and 405 nm, which are beyond the absorption edge of the photoresist (310 nm), we compare the resulting cross-sectional etching volumes. The volumes were larger when 325 nm light was employed, i.e., closer to the absorption edge. Although 405 nm light did not cause structural change in the photoresist, a higher reduction of the surface roughness was observed as compared to the 325 nm light. These results indicate that even wavelengths above 325 nm can cause surface roughness improvements without notably changing the structure of the photoresist.

Subsurface Atomic Structure of 4H-SiC (0001) Finished by Plasma-Assisted Polishing

2013 ◽  
Vol 740-742 ◽  
pp. 435-438
Author(s):  
Hui Deng ◽  
Kazuya Yamamura
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Water Vapor ◽  
Oxidation Rate ◽  
Smooth Surface ◽  
Silicon Oxycarbide ◽  
Plasma Oxidation ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Single Crystal Sic

Plasma-assisted polishing (PAP) was proposed for finishing difficult-to-machine materials, such as single-crystal SiC, reaction-sintered SiC, diamond, and sapphire. In the case of PAP application to the finishing of the 4H-SiC surface, an atomically smooth surface without any scratches was obtained. In this study, we observed 4H-SiC (0001) surfaces processed by water vapor plasma oxidation and PAP using ceria abrasives through cross-sectional transmission electron microscopy (XTEM). Water vapor plasma oxidation was conducted for 1 min, 5 min and 60 min. An intermediate layer located between SiO2 and SiC, which corresponds to silicon oxycarbide, was clearly observed in the case of a short oxidation. As oxidation time increased from 1 min to 60 min, average oxidation rate decreased from 2.7 nm/min to 0.6 nm/min. An atomically smooth 4H-SiC (0001) surface was obtained after PAP for 60 min using ceria abrasives.

Cross-sectional TEM and corrosion studies of Al and N implanted copper

1987 ◽  
Vol 93 ◽  
Author(s):  
E. Gerritsen ◽  
H. J. Ligthart ◽  
T. E. G. Deenen
Keyword(s):  
Electron Microscopy ◽  
High Dose ◽  
Copper Sulphide ◽  
Cross Sectional ◽  
Damage Layer ◽  
Implantation Damage ◽  
Transmission Electron ◽  
Corrosion Studies ◽  
Copper Single Crystals

ABSTRACTPoly- and single crystalline copper was implanted with aluminium and nitrogen at doses ranging from 1016 to 5 × 1017 at/cm2 and energies of 170 keV. The corrosion resistance of the implanted surfaces was tested by exposure to an H25-containing atmosphere. The amount of copper sulphide formed was measured by chrono potentiometric reduction. The amount of corrosion products was markedly reduced (up to a factor 50) by high dose implantations of aluminium. The microstructure of the implanted copper was examined by Transmission Electron Microscopy of cross-sectioned specimens. A deep damage layer far exceeding the ion range was observed. XTEM-pictures of aluminium implanted copper single crystals of various orientations suggest a channeling mechanism for this deep damage layer. In situ annealing of the specimens in the TEM showed that most of the implantation damage is removed at 600°C except for an array of dislocations at the end of the damage range.

Anisotropic Surface Roughness in Strain Relaxed In0.40GA0.60As on Gaas with a Step-Graded InxGA1-xAs Buffer Layer

1993 ◽  
Vol 312 ◽  
Author(s):  
J. C. P. Chang ◽  
B. K. Kad ◽  
S. R. Nutt ◽  
K. L. Kavanagh
Keyword(s):  
Electron Microscopy ◽  
Surface Roughness ◽  
Buffer Layer ◽  
Strain Relaxation ◽  
Phase Segregation ◽  
Periodic Variation ◽  
Cross Sectional ◽  
Anisotropic Surface ◽  
Transmission Electron ◽  
Plane Direction

AbstractWe report the structural characterization of the 3-D relaxation morphology of In0.4Ga0.6As grown on a step-graded InxGa1-xAs buffer layer on GaAs. Scanning electron microscopy showed “grooves” spaced on the order of microns running only in the [110] direction. Each groove was observed with cross-sectional transmission electron microscopy to mark the location of a vertical low-angle tilt and/or twist boundary. The veiy rough layer morphology may be the result of island coalescence or severe surface roughness that created the grain boudnaries as the layer grew. Strain relaxation in the In0.4Ga0.6As layer was much reduced in the [101] in-plane direction. The asymmetry in residual in-plane strains in the In0.3Ga0.7AS layer and/or the increased In composition may be responsible for the development of an anisotropic surface roughness. X-ray microanalysis revealed a periodic variation in layer composition which correlated with a fine contrast modulation presumably the result of phase segregation.

Analysis of epitaxial CoSi2/Si and Si/CoSi2/Si heterostructures

1986 ◽  
Vol 44 ◽  
pp. 730-731
Author(s):  
N. Lewis ◽  
E. L. Hall ◽  
B. D. Hunt ◽  
L. J. Schowalter
Keyword(s):  
Integrated Circuits ◽  
Ohmic Contacts ◽  
Fluorite Structure ◽  
Metal Silicide ◽  
Cross Sectional ◽  
Metal Base ◽  
Substrate Side ◽  
Transmission Electron ◽  
Device Applications

The formation of thin epitaxial metal silicide layers on Si and Si/metal silicide/Si heterostructures has received considerable attention recently for applications as ohmic contacts, permeable and metal base transistors and 3-D integrated circuits. Cobalt disilioide (CoSi2) is promising for these applications because its cubic fluorite structure is similar to that of Si. In addition, the lattice parameters of CoSi2 and Si are reasonably close (-1.2% mismatch at room temperature) making this system attractive for epitaxial growth. The quality of the epitaxial layers is particularly important for device applications. In this paper the microstructures of several CoSi2/Si and Si/CoSi2/Si specimens were investigated using transmission electron microscopy. Planar and cross-sectional samples were prepared. The planar specimens were first mechanically ground from the Si substrate side and then ion-milled in argon.

Microstructure and Size Distribution of Compound Semiconductor Nanocrystals Synthesized by Ion Implantation

1998 ◽  
Vol 536 ◽  
Author(s):  
A. Meldrum ◽  
S. P. Withrow ◽  
R. A. Zuhr ◽  
C. W. White ◽  
L. A. Boatnerl ◽  
...  
Keyword(s):  
Ion Implantation ◽  
Semiconductor Nanocrystals ◽  
Compound Semiconductor ◽  
Fused Silica ◽  
Silica Matrix ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Host Materials ◽  
Device Applications ◽  
Versatile Technique

AbstractIon implantation is a versatile technique by which compound semiconductor nanocrystals may be synthesized in a wide variety of host materials. The component elements that form the compound of interest are implanted sequentially into the host, and nanocrystalline precipitates then form during thermal annealing. Using this technique, we have synthesized compound semiconductor nanocrystal precipitates of ZnS, CdS, PbS, and CdSe in a fused silica matrix. The resulting microstructures and size distributions were investigated by cross-sectional transmission electron microscopy. Several unusual microstructures were observed, including a band of relatively large nanocrystals at the end of the implant profile for ZnS and CdSe, polycrystalline agglomerates of a new phase such as γ-Zn 2SiO4, and the formation of central voids inside CdS nanocrystals. While each of these microstructures is of fundamental interest, such structures are generally not desirable for potential device applications for which a uniform, monodispersed array of nanocrystals is required. Methods were investigated by which these unusual microstructures could be eliminated.

Research on Fabricating CVD Diamond Microstructures Using RIE Process

2009 ◽  
Vol 407-408 ◽  
pp. 41-44
Author(s):  
Wen Chen Chou ◽  
Choung Lii Chao ◽  
Wei Haw Fan ◽  
Kung Jeng Ma
Keyword(s):  
Electron Microscope ◽  
Aspect Ratio ◽  
High Hardness ◽  
Etching Time ◽  
Micro Structure ◽  
Transmission Electron ◽  
Chemical Inertness ◽  
Mask Material ◽  
Before And After ◽  
Afm Probe

Diamond is one of the most important engineering materials for its extreme hardness, high thermal conductivity value and chemical inertness. Due to its high hardness and strength, it can be ideal candidates for AFM probe or micro-needle. In this research, micro cone-like shaped diamond tips with high aspect ratio formed using reactive ion etching (RIE) method. The scanning electron microscope (SEM), transmission electron microscope (TEM) and micro-Raman spectroscopy were used to study the surface morphology and sub-surface micro-structure before and after RIE process. The results showed that gold could be adopted as mask material during the RIE process. Different microstructures could be obtained using different RIE parameters such as etch duration and reactant gas. After RIE (O2 50sccm, 200W) for 5min the micro cone-like structures (aspect ratio~8) could be observed on the surface if a thin layer of gold was applied as mask. However, under the same RIE conditions, the irregular pillar-like microstructures started to emerge if the etching time was stretched longer.

High Quality in.Ga1−xas Heterostructures Grown on GaAs With Movpe

1998 ◽  
Vol 510 ◽  
Author(s):  
M.T. Bulsara ◽  
E.A. Fitzgerald
Keyword(s):  
Surface Roughness ◽  
Phase Separation ◽  
Threading Dislocation ◽  
Misfit Dislocations ◽  
Cross Sectional ◽  
Plan View ◽  
Force Microscopy ◽  
Optimum Growth Temperature ◽  
Transmission Electron ◽  
Metal Organic

AbstractInxGa1−xAs structures with compositionally graded buffers were grown by metal-organic vapor phase epitaxy (MOVPE) on GaAs substrates and characterized with plan-view and cross-sectional transmission electron microscopy (PV-TEM and X-TEM), atomic force microscopy (AFM), and x-ray diffraction (XRD). The results show that surface roughness experiences a maximum at growth temperatures where phase separation occurs in InxGa1−xAs. The strain energy due misfit dislocations in the graded buffer indirectly influences phase separation. At growth temperatures above and below this temperature, the surface roughness is decreased significantly; however, only growth temperatures above this regime ensure nearly complete relaxed graded buffers with the most uniform composition caps. With the optimum growth temperature for grading InxGa1−xAs determined to be 700°C, it was possible to produce In0.33Ga0.67As diode structures on GaAs with threading dislocation densities < 8.5 × 106/cm2

Epitaxial Thin Films And Heterostrcutures of Various Isotropic Metallic Oxides for Device Applications

1994 ◽  
Vol 341 ◽  
Author(s):  
C. B. Eom ◽  
Julia M. Phillips ◽  
R. J. Cava
Keyword(s):  
Thin Films ◽  
Cuprate Superconductors ◽  
Superconducting Devices ◽  
Epitaxial Thin Films ◽  
Metallic Oxide ◽  
Cross Sectional ◽  
Lattice Match ◽  
Metallic Oxides ◽  
Transmission Electron ◽  
Device Applications

AbstractWe have grown epitaxial thin films of various isotropic metallic oxides such as Sr1-xCaxRuO3 and La8-xSrxCu8O2Oin situ by 90° off-axis sputtering. These metallic oxides are pseudo-cubic perovskites with essentially isotropic properties, which could be ideal normal metals for SNS junctions in superconducting devices and for electrodes in ferroelectric devices. We have fabricated epitaxial ferroelectric heterostructures [SrRuO3/Pb(Zr0. 52 Ti0.4 8) O3 /SrRuO3] employing isotropic metallic oxide (SrRuO3) electrodes on substrates of (100) SrTiO3 and (100) Si with an yttria stabilized zirconia buffer layer. They exhibit superior fatigue characteristics over those made with metal electrodes, showing little degradation over 10 cycles, with a large remnant polarization (27 μC/cm2 ). We have also grown epitaxial superconducting heterostructures (YBa2Cu3O7 / La8-xSrxCu8O2O / YBa2Cu3O7 ) with a copper-oxide-based isotropic metallic oxide (La8-xSrxCu8O20) normal metal barrier. X-ray diffraction and cross-sectional transmission electron microscopy reveal these heterostructures to have high crystalline quality and clean interfaces. This material will facilitate fabrication of ideal SNS Josephson junctions with low boundary resistance due to its excellent chemical compatibility and lattice match with cuprate superconductors and will be useful for determining the source of interface resistance in such heterostructures.

InGaAs/InP Multiquantum well Structures Grown by Trichloride Vapor Phase Epitaxy

1989 ◽  
Vol 145 ◽  
Author(s):  
K. W. Wang ◽  
V. D. Mattera ◽  
K. Tai ◽  
S. N. G. Chu ◽  
D. D. Roccasecca ◽  
...  
Keyword(s):  
High Speed ◽  
High Performance ◽  
Stark Effect ◽  
Optical Modulators ◽  
Double Crystal ◽  
Cross Sectional ◽  
High Modulation ◽  
Transmission Electron ◽  
Device Applications ◽  
Multiquantum Well

AbstractLong wavelength (l.3pm<X<l.551un) InGaAs/InP multiquantum well (MQW) PIN structures in which the quantum confined Stark effect can be observed, are of particular interest because of their potential for high modulation contrast ratios and high speed operation. The chemistry of trichloride VPE lends itself to the growth of high purity InGaAsP heterostructures which are essential for the realization of high performance optical modulators and switches. In this study, we investigate the application of multi-frit trichloride VPE for the highly uniform epitaxial growth of InGaAs/InP MQW structures on two-inch InP substrates for advanced photonic device applications. The growth of MQW structures with various well thicknesses was studied as was the effect of substrate orientation. The structures have been characterized by infrared absorption and photoluminescence spectroscopy, cross-sectional transmission electron microscopy and double crystal x-ray diffraction.

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